A common ophthalmological surgical technique is the removal of a diseased or injured lens from the eye. Earlier techniques used for the removal of the lens typically required a substantial incision to be made in the capsular bag in which the lens is encased. Such incisions were often on the order of 12 mm in length.
Later techniques focused on removing diseased lenses and inserting replacement artificial lenses through as small an incision as possible. For example, it is now a common technique to take an artificial intraocular lens (IOL), fold it and insert the folded lens through the incision, allowing the lens to unfold when it is properly positioned within the capsular bag. Similarly, efforts have been made to accomplish the removal of the diseased lens through an equally small incision.
One such technique is known as phacoemulsification. A typical phacoemulsification tool includes a hollow needle to which electrical energy is applied to vibrate the needle at ultrasonic frequencies in order to fragment the diseased lens into small enough particles to be aspirated from the eye. Commonly, an infusion sleeve is mounted around the needle to supply irrigating liquids to the eye in order to aid in flushing and aspirating the lens particles and cortical material through an aspiration port formed in the hollow needle.
It is extremely important to properly infuse liquid during such surgery. Maintaining a sufficient amount of liquid prevents collapse of certain tissues within the eye and attendant injury or damage to delicate eye structures. As an example, endothelial cells can easily be damaged during such a collapse and this damage is permanent because these cells do not regenerate. One of the benefits of using as small an incision as possible during such surgery is the minimization of leakage during and after surgery which aids in the prevention of such a collapse.
One way to ensure infusion of a sufficient amount of liquid into the eye during an operation is to regulate the flow of irrigating liquid through the sleeve. For example, during phacoemulsification the aspiration port on the phaco needle can become occluded with lens fragments or particles. If the sleeve is of the type having an infusion port at its tip, surrounding the needle, it may also become occluded. When this happens, flow of irrigating liquid into the eye may decrease, meaning that not enough liquid flow may be available to help clear the occlusion. If the surgeon acts to increase liquid flow through the infusion sleeve. This can cause an increase in the Reynolds number of the infusion liquid to the point where the liquid flow become turbulent which can, in itself cause damage to the eye.
Flow control may also be desirable for sleeves having discharge ports that direct the liquid toward the needle tip may create a flow pattern that pushes lens or cortical material away from the aspiration port of the needle, prolonging the phaco procedure.
Instruments using various types of infusing sleeves are well known and well-represented in the art and exemplify the attempts made by others to address the problem of maintaining an adequate flow of irrigating liquid without causing damage to the eye.
U.S. Pat. No. 4,643,717 (Cook et al) teaches and describes an aspiration fitting adapter formed as a sleeve concentric to the phaco needle and having a pair of bilaterally opposed discharge ports formed proximate the end of the sleeve to infuse irrigating liquid into the eye.
U.S. Pat. No. 5,151,084 (Khek) teaches and describes an ultrasonic needle with an infusion sleeve that includes a baffle. The sleeve of Khek also fits concentrically about the needle and allows the needle to protrude a substantial distance therefrom while providing pair of discharge ports bilaterally opposed to each other near the terminus of the sleeve.
U.S. Pat. No. 6,117,151 (Urich et al) teaches and describes an eye incision temperature protection sleeve fitted concentrically about a needle and having a single discharge port through which irrigating liquid is passed.
U.S. Pat. No. 6,605,054 (Rockley) teaches and describes a multiple bypass port phaco tip having multiple aspiration ports and a single discharge port to infuse liquid into the eye.
U.S. Pat. No. 5,879,356 (Geuder) teaches and describes a surgical instrument for crushing crystalline eye lenses by means of ultrasound and for removing lens debris by suction which demonstrates the use of a sleeve positioned concentric to the needle and having a pair of discharge ports formed thereon.
A series of patents issued to Richard J. Mackool illustrates further variations of irrigating sleeves. Mackool forms the sleeve with a somewhat flattened cross-section configuration intended to more closely approximate the shape of the incision through which the sleeve is inserted into the eye. This cross-section can be seen at FIG. 3 of U.S. Pat. No. 5,084,009.
U.S. Pat. No. 5,084,009 (Mackool) teaches and describes a liquid infusion sleeve for use during eye surgery with the sleeve having a flattened cross-section and having a pair of infusion ports formed on the forward portion of the flattened section.
U.S. Pat. No. 5,286,256 (Mackool) teaches and describes a liquid infusion sleeve having a free-floating rigid sleeve surrounding a needle which is intended to prevent the outer flexible sleeve from collapsing onto the needle.
U.S. Pat. No. 5,354,265 (Mackool) teaches and describes a liquid infusion sleeve showing yet another construction intended to keep the outer flexible infusion sleeve from collapsing onto the vibrating needle.
U.S. Pat. No. 5,505,693 (Mackool) teaches and describes a method and apparatus for reducing friction and heat generation by an ultrasonic device during surgery incorporating a needle support to prevent collapse of the outer flexible sleeve.
The Mackool patents are characterized by a pair of discharge ports formed at the distal end of the sleeve through which irrigating liquid is passed into the eye during the operation.
U.S. Pat. No. 5,645,530 (Boukhny) teaches and describes a phaco emulsification sleeve, one variation of which has a bellows portion attached to a discharge port ring which directs an annular flow of liquid around the needle and into the eye. The use of the bellows is intended to allow the sleeve to absorb spikes in liquid pressure during the operation.
U.S. Pat. No. 5,634,912 (Injev) teaches and describes an infusion sleeve having a rotating tip to allow the phaco needle to be repositioned during surgery. The top also has a single discharge port for infusing liquid during surgery.
Published U.S. Patent Application 2003/0004455 (Kadziauskas) teaches and describes a bi-manual phaco needle using separate emulsification and aspiration needles inserted into the eye simultaneously during surgery.
U.S. Pat. No. 6,007,555 (Devine) teaches and describes an ultrasonic needle for surgical emulsification and details the tendency of some ultrasonic phaco needles to force lens fragments away from the needle's aspiration port.
U.S. Pat. Nos. 6,299,591, 6,159,175, 5,743,871, 5,741,226 and 5,725,495 (Banko) all teach and describe a phacoemulsification handpiece, sleeve and tip, with the sleeve having permanently fixed exterior and/or internal baffles thereon to direct the flow of irrigation fluid away from the needle's aspiration port. The external baffles effectively increase the diameter of the sleeve while the internal baffles are relatively difficult or expensive to manufacture as compared to an extruded sleeve.
U.S. Pat. No. 7,601,135 (Akahoshi) teaches and describes a multi-port infusion sleeve with ports formed on the curved portion of the sleeve proximate the end thereof.
U.S. Pat. No. 7,601,136 (Akahoshi) teaches and describes an infusion sleeve with ports formed on the curved portion of the sleeve proximate the end thereof.
The need exists for an improved infusion sleeve which allows for a greater volume of liquid to be infused into the eye while avoiding the problems described in the prior art with respect to pushing lens and cortical material away from the aspiration port or damaging delicate eye tissue impacted by such direct flow due to increased pressure, turbulence and the like.
The need also exists for such improved infusion sleeves to incorporate a flow-directing expedient that does not extend above the surface of the sleeve during insertion and removal of the phaco needle through the incision.
The need also exists for such improved infusion sleeves to be simple in construction, efficient in operation and economical to manufacture.
In accordance with a first preferred embodiment of the present invention, a phaco infusion sleeve has at least one infusion liquid discharge port thereon formed by severing a portion of the sleeve to create a flap which, responsive to an increase in the flow of the irrigation liquid, swings out to direct the liquid in a desired direction. One such configuration directs the liquid flow away from the needle tip to limit the extent to which lens and cortical material are pushed away from the phaco needle.
In accordance with another preferred embodiment of the present invention, a phaco infusion sleeve has at least one infusion liquid discharge port on the lateral part of the sleeve. The port has at least one slit beginning at the periphery of the port and extending a selected distance away from the port. Under normal flow conditions the slit remains closed and the flow of liquid is directed through the undistended port. When an occlusion of the aspiration port occurs and increased pressure in the eye causes the flow of infusion liquid to back up the slit is forced open, increasing the cross-sectional area of the port available for liquid flow allowing a larger volume of liquid to enter the eye more safely.
While the following describes a preferred embodiment or embodiments of the present invention, it is to be understood that this description is made by way of example only and is not intended to limit the scope of the present invention. It is expected that alterations and further modifications, as well as other and further applications of the principles of the present invention will occur to others skilled in the art to which the invention relates and, while differing from the foregoing, remain within the spirit and scope of the invention as herein described and claimed. Where means-plus-function clauses are used in the claims such language is intended to cover the structures described herein as performing the recited functions and not only structural equivalents but equivalent structures as well. For the purposes of the present disclosure, two structures that perform the same function within an environment described above may be equivalent structures.
These and further aspects of the present invention will become apparent upon consideration of the accompanying drawing figures in which: